DE2435702A1 - ABSORBENT MATERIAL, METHOD FOR MANUFACTURING IT, AND DEVICE FOR CARRYING OUT THE PROCESS - Google Patents

Description

Applicant: T. J. SMITH 4 NEPHEW LIMITED

Title:

Absorbent material, process for its manufacture and device for carrying out the method

description

The invention relates to an absorbent material in particulate form porous shape. It also relates to a method of making absorbent material of this type. It relates to furthermore an apparatus for coating particulate material according to this method.

The invention is concerned with the treatment of particulate! absorbent material, e.g. porous polystyrene granu-Lafcj but especially absorbent carbon granulate, it is

Applicable for the treatment of such granules, which have no or only a slight IU fan 3 or no fineness or fineness, 3i -:> LbI particularly valuable for the loading of K-.jhLete iiüiiea, the ssutoc of fineness (dust) or ob ^ Surfaces & office floors are freed by washing. The fact that JBra-mgnis is useful in chemical processes in general is particularly useful where purity is essential, for example in the treatment of food and beverages

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and especially in a medical context.

Useful particulate coals in the medical field, e.g. the detoxification of blood are known. However, they have the disadvantage that they tend to be very fine particles of coal or Bringing impurities into the bloodstream, causing disintegration of blood cells on rough particle surfaces due to turbulence and, in particular, leads to platelet adhesion, the -Uo Platelet count can decrease by $ 50 or more.

The present invention creates a material that solves this problem me diminishes or overcomes, and consists first of all in la3 the Particles with a protective, permeable layer over olar are provided on the particle surface, the layer and consists of a blocompatible polymer and eirian meah-misohwn iJ -},? ~ Prevents the fall of the particles and a smooth lurehläijüigi) surface guaranteed without the pores of the Matarialj au τβ s

It is particularly expedient and advantageous if H; at; hüts- »ii de layer about 1 blue micron dioc iat. ßöBond> t ··! ζχζνΜηΜΙζ and rorteilhaffc is ea autjh, if, the SchUfcaende Joh «.," ■ · ■ * i durr.h evaporation of a solution ijs Poljmerd isaugt iat,

Dae Täilchenmatsrlal iat voraugaw ^ tse KOhIe ₅ zJ, aiii · -! I tfe Speakiaan Art 6ΙΠ, 5 bia 10 Maechen size, harge ^ t-ils u ■; -.-. ά;.) ^, ^ - nut-Schalej but also granules Pol / atyrol-Baüla jer- kd.m turns are as untar of ßöhm unl Haas beselohmmgen eg the affairs XAD2, IAJ) 4 and XAD? is expelled, Die Gröflen

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BATH ORIGINAL

of the absorber particles, for example the coal particles, can by far Scope vary; however, sizes below 40 mesh are preferred; where e.g. mesh sizes 5 - 10, 18 - 40, 10 - 16, 16-30 are usable.

The bicompatible polymer is e.g. polyhydroxyethyl methacrylate, hereinafter called PoIyHEMA, cellulose acetate, polyurethane, Silicone or polyamide.

The polymer is e.g. in a proportion of up to 20% by weight of the absorbent material is present. Preferably it is present in proportions from 0.25 to 5 #, e.g., about 3% by weight. It is desirable to use as little as what is agreed with a good coating.

The absorbent material, for example charcoal, used in the process is in turn processed by a treatment process in which a bed, a layer of particulate material is exposed to an upward flow of treatment liquid to such an extent that the individual particles are set in vigorous motion and delicacies are removed from the particles in the liquid stream, whereby the bed remains as a whole and no additional delicacies (dust) are sucked out by abrasion. This washing process also aims to localize the concentration of insoluble impurities on the upper and / or or the lower end of the treatment * set «weeks later Removal, since such insoluble impurities are dependent on

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ability tone of their size, shape, specific gravity, of the Type of treatment liquid and the flow strength of the treatment liquid, either to the bottom of the treatment bed fall or climb to the top of the bed. The fluid itself can be used to To impregnate material with a biocompatible polymer before a coating according to the invention is carried out.

The invention is also directed to a method of treating porous particulate absorbent material, such as charcoal, in which a heated mass of particles, their individual Particles move relative to one another can never get imposed, be sprayed with a solution of biocompatible, biocompatible polymer to such an extent that that the solvent evaporates and leaves a layer over or on the particle surface. These particles are e.g. impregnated with the same or a different biocompatible polymer.

The particles in the mass are in a rapid relative motion offset by falling on an inclined surface such as an inclined rotating pan, or represented as a violently agitated spray such as a "boiling" bed will. In either case, the mass of the particles is preferably brought into a heated state by means of a stream of heated air held.

The solution for spraying the particles is, for example, an aqueous • —5—

509807/0829

ithanol solution from PoIyHEMA. or a toluene solution of silicone resin. In the former pail is the ratio of water to

Ethanol by volume preferably 10:90 to pure Xthanol, e.g. 5: 95 in terms of volume.

It is possible to provide that the sprayed-on layer contains a proportion of "micronized", i.e. very much in part a NaCl or other water-soluble salt, so that the permeability the polymer layer is improved after a subsequent leaching.

A suitable temperature to which the part "henmaterial for example, is heated before it is sprayed, is from 30 to 100 ° C, preferably from 35 ° to 70 ° 0, for example at 40 ⁰ G. GGGF. is the part marriage material thoroughly after spraying dried by being heated to a higher temperature, for example at about 100 ⁰ C to 150 ⁰ C, for example about 12O ⁰ C.

In a modification of the above-mentioned method, a solution of a monomer is used which, on contact with the heated Polymerized mass; however, this can have the major advantage that a catalyst is usually necessary to promptly add to the monomer polymerize, whereby the catalyst can contaminate the material.

As further described above, another "desirable feature of the process is that the coal particles in a suitable impregnation agent can be dipped in order to modify its properties before coating. You beforehand

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The washing method in writing represents a simple ¥ eiae, the To impregnate coal parts.

The invention also provides an apparatus for implementation of the method described in Torher for coating particles which is characterized in that it comprises means for, inter alia, applying the bulk of the porous absorbent material

hold while every single glow of a ^ relative movement is subjected; a spray head to feed a solution of a biocompatible polymer to this mass; a facility for Heating the mass.

Such a gate direction includes, for example, a vessel around a very creating vigorous, turbulent spray or agitation; se.B. a vessel for a fluidized bed, or an inclined one rotating pan, which is a suitable means of taking up the mass of coal particles.

Preferably the means for heating comprises means for Supply of hot air, such as is used to set the particles in motion or is directed onto the particles in the rotating pan.

The Torilegende invention also consists in a method for Detoxify blood working with absorbent porous granular material, e.g. coal, coated according to the foregoing.

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The invention is further described below with reference to the drawing, in preferred embodiments of the invention are shown. In the drawing, FIG. 1 shows an arrangement with a vessel and a liquid flow circuit for carrying out a washing treatment of particulate coal,

2 is a view of a device for coating particulate coal;

3 shows a further device for coating particulate coal,

Fig. 4 shows a spray device for coating particulate coal and Figures 5, 6 and 7 are photomicrographs of coal particles.

According to FIG. 1, a pump 1 feeds liquid into the lower end of a treatment vessel 2, at the upper end of which the liquid exits again, flows through a 3Ω filter and over Valves V1 and V2 goes back to the pump.

The vessel 2 has a transverse gauze 4 or similar perforated support means which supports a bed of particulate charcoal to be treated. It also has exits 5 and 6 in the form of valved tubes.

During use, suitable charcoal is placed on the gauze 4 and the treatment liquid, which is typically 50:50 aqueous ethanol by volume, is passed around the pump 1 to such an extent by the flow circle.

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pumps that particles are set in violent motion; i.e. they rotate and move about their own axis in relation to one another, but they do not make any translational movements to one another to such an extent that the completeness of the bed is destroyed.

Initially, fineness is swept through the bed of moving particles using a strong flow of liquid and collected in the filter 3. Heavy particle-shaped impurities, for example mineral impurities such as eggs, sand or metal particles, move downwards through the bed as a function of their size, shape, density, the type of liquid and the extent of the liquid flow and collect as a layer 7 on the gauze 4. Lighter contaminants, such as wood, ash or bones, in turn move upward through the bed, depending on the factors just mentioned, and collect, for example as a layer 8, on top of the essentially calm bed from individually set in motion Particle Ie valves V1 and 72 are then operated in such a way that water enters at 9, which continuously washes out the aqueous alcohol. This is typically done at a lower flow rate than the initial process stage. Optionally at this stage introduces an additional washing with hot, for example 60 ° to 70 ⁰ C hot water, improved results.

The layers 7 and 8 are then drawn off laterally through the pipes 5 and 6, respectively, while the pump is still working. Mostly will • —9— *

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the upper layer 8 peeled off before the lower layer 7. Thereafter the pump is turned off and the slurry, the sludge of coal, which has been cleaned of subtleties and impurities, is deducted at 5.

According to FIG. 2, an inclined, 40.64 cm rustproof enrobing pan 21, which rotates according to arrow A and is mounted on a stand 22, contains three kilograms of coal particles 23 which have been cleaned of fineness and impurities and possibly with a biocompatible polymer or another previously described impregnation agent. These particles are heated by hot air 55 ⁰ C to 45 ⁰ C, through the line 24 with 0.566 m ⁵ / min conveyed and placed on the pan. The heated particles are sprayed intermittently or continuously over the spray head 25 while they are in a violent falling motion with a fine spray of 4 weight ^ solution of polyHEHA polymer in aqueous ethanol in a volume ratio of 5:95 # to a total Absorption of 3 ue <-weight polymer in relation to the carbon. Because the "amount of heat from the hot coal is much greater than that of the spray material impinging it, the solvent evaporates rapidly, forming the polymer one over, or in some cases substantially on the surface of the coal particles;" this layer is only biocompatible, ie compatible, due to the nature of the polymer, but also binds the particles against abrasion, which could create new fineness, and forms a smooth surface, which prevents the adhesion of blood platelets and the decomposition of the blood or a similar breakdown to do a Xhnliok-

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Prevents world-sensitive liquid that subsequently flows over it.

The product can be distinguished from just impregnated carbon by immersion using solutions. For those coals in which the solutes are smaller inorganic molecules, the impregnation is essentially uniform throughout the particle. Where polymer solutions are proposed in the known prior art, e.g. in PR-PS 7 103 838, the effective impregnation is much deeper than in the present invention, since in the known method the particles last for a relatively long period of time, Typically, it takes two minutes to come into contact with liquid before the liquid is absorbed by the pores. Accordingly, the particles must contain precipitation everywhere. On the other hand, the method according to the invention covers the particles only over or on the surface. The use of a large "body" of coal particles and a fine spray _9, which causes the solvent to evaporate quickly and leave the polymer only on and in the surface, ensures that the pores remain essentially unclogged, like Pig. 6 and 7 »own. Furthermore, a product in which an impregnation treatment is followed by a spray treatment according to the invention can be distinguished under the electron microscope from both an impregnated product and a product that has only been treated.

Although the present announcement is concerned by any of the theoretical basis of the invention described herein-

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The findings should not be determined, but it can be assumed that only one impregnation process, although it because of the covering of the interior of the pores, a larger proportion of the area covered, but a coal is obtained which still has a rough and broken surface, easily tearable and tends to break down into small particles. The spray process avoids this and provides a particle with smoother Surface that is free of surface debris and yet provides a carbon with the useful absorbance that is customary is determined by the permeability of the thin, essentially uniform layer, which is typically one to ten times 10 to 7 cm / see. amounts to.

The absorption of materials to coal 610 is studied using the thrust system. A known amount of washed and dried charcoal 610, either untreated or treated as set forth below, is placed in a known amount of a paracetamol solution. This is placed in a 37 ⁰ O shaking water bath. For an analysis after four hours, examples are taken from the infusion solution. Since the initial concentration and the solution volume of the adsorbate and the amount of adsorbent used are known, the amount absorbed can be determined.

The following results are available:

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Uncovered charcoal 250 mg / gm.

2 $> impregnated (PoIyHEMA) 235 mg / gm.

4 # impregnated (PoIyHEMA) 225 mg / gm.

2 # spray-covered (PoIyHEMA) 220 mg / gm.

4 # spray-covered (PoIyHEMA) 195 mg / gm.

Spray-covered material according to the invention, under these circumstances, has absorption properties which are not essential are inferior to the uncovered or impregnated material.

However, spray covered material shows advantages in that the loss of free particles to the liquid stream is reduced. This is measured by taking different coals, whether untreated or treated, one after the other in the order: unwashed ;, uncovered; washed, uncovered; OJi bath solution, 2 # spray; $ 0 bath solution, 4 # spray; 1.89 # bath solution, $ 0 spray; 3.75 # bath solution, $ 0 spray; and 2.82 # bath solution, 3.0796 spray.

A column is filled with 315 g of coal and a total of 20 1 of normal 156 saline solution is sent through the column, one liter at a time in one direction, and at 1750 ml / min. A colter counter analysis of each example is performed to determine the number of TtHe that are greater than 2fx and greater than 5 / * -.

The typical result is:

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Average number / ml only with s 2μτη. Volume through
Column (ε) unwashed
unrelated washed
based 0 + 2 0 + 4 1.89 + 0 3.75 + 0 3 + 3 Average number / ml only with ^ 2yum Volume through
Column (I) unwashed
unrelated washed
based 0 + 2 .0 + 4 1.89 + 0 3.75 + 0 3 + 3 1
3
6th
12th 1,396,700
152.764
27,364
15.514 40.655
6.267
2,319
791 9,972
1.188
476
192 9.505
780
391
184 115.062
8.986
7.145
6.609 34.662
2,412
1.291
1.136 11.305
1.636
692
953 1
3
6th
12th 15.988
378
83
38 524
62
69
29 558
93
39
30th 282
61
51
19th 2,200
412
249
135 470
192
107
70 429
76
44
78

When graphing the results obtained for all twenty versions, it appears that not only does spray coating give better results than impregnation, but that even after twenty reversals, the spray-related particles still improve, whereas dipped particles do have reached constant and high value.

Figure 3 shows an alternative way of producing a similar coating. A vessel 36 has an air inlet 37 at the bottom and an air outlet 38 at the top. The inlet 37 becomes hotter Air fed by a pump 39 and a heater 310 "this air serves to set a bed of coal in motion violently, carried by a gauze or similar support means 312. A fine spray of polymer solution is placed over the bed at 313 supplied, with solvent vapor «with the air through quickly blown out the outlet. Here, too, brief contact leads to a low-thermal hatred of solvents an inherently agile high thermal hatred of hot coal to effective surface lowers of the polymer.

I ¹ Ig. 4 shows a typical device for supplying air to the spray head 25 according to FIG. 2,

Air is fed with 1814.36 - 3628.72 g per 6.452 cm ² at 41 to a carbon filter 42, leaves this at 43 and passes a beduxing valve 44 old Aueläitn 45 and 43 with a pressure of 15875.65 g per 6.452 om ² . Another reducing valve 47

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reduces the air exiting outlet 45 and at the top Part of the pressure vessel 48 flows through the inlet 49, on

the pressure of 1360.77 gr per 6.452 cm. This pressure vessel contains in its lower part at 40 1500 ml of a 4 weight ^ PolyHEMA solution, which is pressed through a line 51 under pressure to the spray head 25 by the last-mentioned air pressure will.

An air outlet 46 leads via an on-off solenoid valve 52, controlled by an electronic timer 43, to an inlet of the spray head, this being the main supply of the

ρ the air conveying the spray agent of 15875 »65 gr per 6.452 cm is. However, another reducing valve 55 is in a line 56 is provided to apply an air pressure of 4535 »90 grams per 6.452 cm to atomize the liquid that through line 51 arrives.

Seven second sprays separated by 53 second drying times have been found useful been. The hot air heating is continued up to five minutes after the completion of the spraying.

Various modifications are within the scope of the inventive concept possible. E.g. it is conceivable to spray coal that is in a shaking vessel, or the heated coal to be sprayed with a solution of a polymerizable monomer, rapid polymerization directly on the carbon surface to effect.

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The product of the process can be used appropriately in a column to detoxify blood that is in the same column ! Dag application filed by the same applicant as the present application, title: "Blood flow column and method for detoxifying blood "(British priority application 35 678/73)».

Thus, another part of the present invention is a particulate porous absorbent material such as this is described above insofar as it is held in a detoxification column made of biocompatible, incompatible material, which is filled with degassed, sterile liquid is.

Figures 5, 6 and 7 show the effect of the enrobing process. In the same 90O magnification is selected in each case. Fig. Figure 5 shows the surface of an unwashed, uncoated coal particle that has a greater amount of fineness than carbon carries loose pollution.

Flg. 6 shows the surface of a washed coal particle with a 2 weight ^ layer of PoIyHEMA, with the surface weakly wavy 1st.

Flg. Figure 7 shows a section through a particle according to Figure 6. The surface layer or skin of PolyHEMA is approximate 5 U, thick and bridges the pores without penetrating or to clog them.

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Claims (19)

Claims 1. Particulate absorbent material in particulate porous form, characterized in that the particles are provided with a protective, permeable layer over or on the particle surface, the layer consisting of a biocompatible polymer and preventing mechanical disintegration of the particles and ensuring a smooth, permeable surface without clogging the pores of the material. 2. Absorbent material according to claim 1, characterized in that the protective layer is about 1 to 10 microns thick. 3. An absorbent material NaOH to claim 1 or 2, characterized in that the protective layer is produced by evaporation of a solution of the polymer. 4. Absorbent material according to one of the preceding claims, characterized in that it consists of coated carbon particles. 5. Absorbent material according to one of the preceding claims, characterized in that the bio-compatible material is a poly-hydroxyethyl methacrylate. -18- 509807/0829 -10- 6. Absorbent material according to one of the preceding claims, characterized in that up to 20 weight ^, preferably 0.25 to 5 weight ^, are made of biocompatible material. 7. Absorbent material according to one of the preceding claims, characterized in that «that it is washed free of delicacies before coating by an upward flow of liquid. 8. A method for producing absorbent material according to any one of the preceding claims, characterized in that a heated mass of particles, which are each offset in relative motion to one another, is sprayed with a solution of the biocompatible polymer to such an extent »that the solvent evaporates and leaves a layer over or on the particle surface. Method according to Claim β, characterized in that the particles are set in relative motion to one another by letting them fall down an inclined surface. 10. The method according to claim 8 or 9, characterized in that the particles are kept in a heated condition by a stream of heated air. 11. The method according to any one of claims 8 to 10, characterized in that the solution of the biocompatible polymer -19-509807 / 0829 an aqueous ethanol solution of poly-hydroxyethyl methacrylate is. 12. The method according to claim 11, characterized in that «that the water: ethanol ratio in terms of volume is from 10:90 to pure ethanol. 13. The method according to any one of claims 8 to 12, characterized in that the material is heated ^{to 30 0} C to 10O ^{0 C before spraying.} 14. A method according to any one of claims 8 to 13, marked in such eichnet characterized in that the particles are immersed in front of the upper pulling in a suitable overdraft agent. 15. Apparatus for coating particulate material according to the method according to any one of claims 8 to 14 » characterized in that it comprises means for holding the mass of the porous absorbent material while each individual particle is subjected to a relative movement; a spray head to deliver a solution of a biocompatible polymer to this mass; a device for heating the mass. 16. The apparatus of claim 15 » dad u rch characterized in that it has a rotatable, inclined pan which receives the mass of the particulate material. -20- 509807/0829 17. Apparatus according to claim 15 or 16, characterized in that the device for heating is a device for supplying hot air which hits the part material. 18. A method for detoxifying blood, characterized in that the blood is brought into contact with the absorbent material according to any one of claims 1 to 7. 19. Particulate absorbent material according to one of claims 1 to 7, characterized in that it is held in a detoxification column made of biocompatible material which is filled with a sterile degassed liquid. 50 9 8 07/0829 Blank page